Canon AE-1 Manual page 13

Closing the Back Cover
Close the back cover until it snaps shut. Gently turn the film rewind crank clockwise in
the direction of the arrow to take up the film slack. Then, advance the film a couple of
times pressing the shutter button until the first exposure appears in the frame counter.
Checking Film Winding
Operate the film advance lever while watching the film rewind knob. If it rotates, the film
is properly loaded. If the rewind knob does not rotate, open the back cover and load the
film again from the start.
Setting the ISO Film Speed
To set the ISO, first push the film advance lever out to its 30° stand-off position away from
the camera body, then lift up the ISO ring around the shutter dial and rotate it in either
direction until the proper number is aligned with the green index mark. ISO is a numerical
rating of a film's sensitivity to light. A higher ISO number indicates a faster film which is
more sensitive to light. On the other hand, a lower ISO number indicates a slower film which
is less sensitive to light. The ISO rating recommended by the manufacturer is printed on the
film box, e.g., ISO 100.
Use of the Memo Holder The memo holder on the camera's back cover is useful for keeping
data like film speed, location, shooting.
After loading the film, set the ISO film speed according to the ISO speed
of the film in use.
The following ISO ratings can be set on the camera. Figures in
parentheses indicate intermediate film speeds.
ISO 25 | 32 | 40 | 50 | 64 | 80 | 100 | 125 | 160 | 200 | 250 | 320 | 400 |
500 | 640 | 800 | 1000 | 1250 | 1600 | 2000 | 2500 | 3200
For example, after tearing off the part of the film box which specifies the
type of the film being used, it can be inserted into the memo holder as a
constant reminder. Personally, I used the memo holder to put an ID-size
photo of my girlfriend.